40' X-31F "Turtle Roof" Double-Door Steel Boxcar -- Pennsylvania Railroad w/Plain Keystone Herald

In the early 1940s, 690 X-31 box cars were converted to X-31F. The original roof sheets were used on the ends and the center sheets were changed to create an interior height of 11'. The cars were used to haul jeeps during World war II. Some of these cars were equipped with automobile loaders. A few of them were still on the Equipment Register in 1967.